Servlet、Thymeleaf和html结合实现：关键字查询

【index.html】

  
  
  
  



  

    
欢迎使用水果库存后台管理系统
    

      
      

        
        请输入查询关键字：
        
      
      添加库存记录
    
    
    

      

        
名称
        
单价
        
库存
        
操作
      
      

        
对不起，库存为空！
      
      

        
        
 苹果 
        
5
        
20
        
        



      
    
    
    

      
      
      
      
    
  

【indexServlet.java】

package com.fruit.servlets;

import com.fruit.dao.FruitDAO;
import com.fruit.dao.impl.FruitDAOImpl;
import com.fruit.myssm.myspingmvc.ViewBaseServlet;
import com.fruit.pojo.Fruit;
import com.fruit.util.StringUtil;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.List;


//servlet从3.0版本开始支持注解方式的注册
@WebServlet("/index")
public class indexServlet extends ViewBaseServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        HttpSession session = request.getSession();

        //设置当前页：默认值为1
        int pageNum = 1;
        //
        String operate = request.getParameter("operate");
        //如果operate!=null，说明：通过表单的查询按钮点击过来的
        //如果operate==null，说明：不是通过表单的查询按钮点击过来的

        String keyword = null;
        if (StringUtil.isNotEmpty(operate) && "search".equals(operate)) {
            //说明是点击表单查询发送过来的请求
            //此时，pageNum应该还原为1，keyword应该从请求参数中获取
            pageNum = 1;
            keyword = request.getParameter("keyword");
            //如果keyword为null，需要设置为""，否则查询时会拼接成 %null%，我们期望的是 %%
            if (StringUtil.isEmpty(keyword)) {
                keyword = "";
            }
            //将keyword把偶才能（覆盖）到session中
            session.setAttribute("keyword",keyword);
        }else {
            //说明此处不是是点击表单查询发送过来的请求，比如点击上一页，下一页或者直接在地址栏输入网址
            //此时keyword 应该从session的作用域获取
            String pageNumStr = request.getParameter("pageNum");
            if(StringUtil.isNotEmpty(pageNumStr)) {
                //如果从请求中读取到pageNum，则类型转换，否则默认为1
                pageNum = Integer.parseInt(pageNumStr);
            }
            //如果不是点击的查询按钮，那么查询是基于session中保存的现有keyword进行查询
            Object keywordObj = session.getAttribute("keyword");
            if (keywordObj != null) {
                keyword = (String) keywordObj;
            }else {
                keyword = "";
            }
        }

        //重新更新当前页的值
        session.setAttribute("pageNum",pageNum);

        FruitDAO fruitDAO = new FruitDAOImpl();
        //List fruitList = fruitDAO.getFruitList();

        List fruitList = fruitDAO.getFruitList(keyword,pageNum);
       // System.out.println(fruitList);

        //保存到session作用域
        session.setAttribute("fruitList", fruitList);

        int count = fruitDAO.getFruitCount(keyword);
        int pageCount = (count + 5 - 1) / 5;
        session.setAttribute("pageCount", pageCount);
        super.processTemplate("index",request,response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }
}

【sql语句】

String sql = "select * from fruit where fname like ? or remark like ? limit ?,5";
        
String sql = "select count(*) from fruit where fname like ? or remark like ?";